In many common applications where composite materials are used to form parts, several factors must be considered simultaneously in the manufacturing process. First, these parts, and thus the composite materials that form them, must provide a surface that may be coated with gel coat and/or an application of decorative paint to provide an attractive visual appeal. Thus, the composite materials must have a high quality smooth finish with no defects throughout the surface of the composite materials. Known in the art as a “Class A” finish, in certain applications, this high quality surface is often a pre-requisite if the parts formed from these composite materials are to be accepted in the marketplace.
Second, these parts must have sufficient stiffness, strength, and durability to withstand long term exposure to the elements. For example, and not meant to be limiting, composite materials used to form parts used in automotive applications must be engineered to withstand exposure to rain, sun, and wind loading, and composite materials used to form parts used in marine applications must be engineered to withstand forces such as exposure to sunlight and salt water. While increasing the strength and stiffness of a part formed of a composite material can most easily be achieved by simply providing additional composite material, such a strategy typically adds undesirable weight and bulk to the resultant part.
Additional thickness and weight in the part is a direct contradiction of the third consideration which is the desire to minimize the weight of these parts. While generally present in all applications, this need is particularly acute in transportation and marine applications, where lower weight results in an overall product having greater fuel efficiency. The desire to lessen the weight of parts used in these applications is most directly accomplished by producing composite materials having greater strength despite having lesser thickness.
However, even a successful strategy for producing thin, durable, high strength, highly stiff, lightweight parts made from composite materials with excellent finishes is still not sufficient. The precursor materials used to form the composite materials used to make these parts must also be relatively inexpensive, and the process used for making the parts must be highly efficient and consistent such that identical parts may be mass produced at a high rate and with minimum cost in materials and labor, or the parts will prove to be cost prohibitive when compared to those known in the art.
Thus, an ongoing challenge is to find the least cost method to produce the lower weight composite materials with sufficient strength, stiffness and durability to withstand high stress loads and harsh operating environments, all while providing a visually appealing surface finish. The present invention addresses those needs.